How to apply lower in a database query for Russian characters?

Question

Ruby on Rails

SQLite3 database. There is a request.

Contract.where("lower(contractor) like :term or lower(subject_contract) like :term", term: "%#{term.mb_chars.downcase}%")

But lower case only works for English characters.
How to fulfill this request for Russian letters as well?

Answer 1

# encoding: utf-8
at the beginning of the file is written?